stomach, the long intestine, and all the rest of those internal
apparatus which are essential for digestion; and then in the same great
cavity, there are lodged the heart and all the great vessels going from
it; and, besides that, the organs of respiration--the lungs: and then
the kidneys, and the organs of reproduction, and so on. Let us now
endeavour to reduce this notion of a horse that we now have, to some
such kind of simple expression as can be at once, and without
difficulty, retained in the mind, apart from all minor details. If I
make a transverse section, that is, if I were to saw a dead horse
across, I should find that, if I left out the details, and supposing I
took my section through the anterior region, and through the fore-limbs,
I should have here this kind of section of the body (Figure 1). Here
would be the upper part of the animal--that great mass of bones that we
spoke of as the spine (a, Figure 1). Here I should have the alimentary
canal (b, Figure 1). Here I should have the heart (c, Figure 1); and
then you see, there would be a kind of double tube, the whole being
inclosed within the hide; the spinal marrow would be placed in the upper
tube (a, Figure 1), and in the lower tube (d d, Figure 1), there would
be the alimentary canal (b), and the heart (c); and here I shall have
the legs proceeding from each side. For simplicity's sake, I represent
them merely as stumps (e e, Figure 1). Now that is a horse--as
mathematicians would say--reduced to its most simple expression. Carry
that in your minds, if you please, as a simplified idea of the structure
of the Horse. The considerations which I have now put before you belong
to what we technically call the 'Anatomy' of the Horse. Now, suppose we
go to work upon these several parts,--flesh and hair, and skin and
bone,--and lay open these various organs with our scalpels, and examine
them by means of our magnifying-glasses, and see what we can make of
them. We shall find that the flesh is made up of bundles of strong
fibres. The brain and nerves, too, we shall find, are made up of fibres,